Hidden Gateways: Tiny Plant Reveals Big Secrets About Seed Growth
Arabidopsis thaliana, a modest weed related to mustard, is the go-to model for plant scientists. Known for its fast life cycle and simple genetics, it has offered insights for years. Yet, this small plant still hides secrets—one of which could transform how we grow crops.
In a recent Current Biology paper, researchers uncovered a brand-new way Arabidopsis nourishes only fertilized ovules, ensuring they grow into seeds. This process may help boost seed size, a key factor in agricultural yield.
Unlike most researchers who study where pollen meets egg in flowers, Ryushiro Kasahara from Nagoya University focused on the area where nutrients enter through the phloem. There, his team discovered a temporary wall made of a molecule called callose. This callose formed a flat barrier, blocking nutrients from reaching unfertilized ovules.
Once fertilization occurred, most of the callose dissolved, forming a ring and allowing nutrients to enter. In unfertilized ovules, the barrier stayed intact. This selective feeding system had never been seen before due to its brief visibility.
The researchers pinpointed an enzyme, AtBG_ppap, that breaks down the callose wall. Disabling the gene for this enzyme led to 8% smaller seeds. Overexpressing it resulted in seeds that were 17% larger. Similar effects were seen in rice, with grain size increasing by 9%.
Scientists believe this discovery could benefit many crops. The study also reminds us how much remains unknown, even in well-studied species.
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